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\IBVShead{5034}{16 February 2001}

\IBVStitletl{The First Ground-Based Photometric}{ Observations of V899 H\lowercase{er}}

\IBVSauth{\"Ozdem\.ir, S.; Dem\.ircan, O.; Erdem, A.; \c{C}\.i\c{c}ek, C.; Bulut, \.{I}.; Soydugan, F.; \\ \indent Soydugan, E.}

\IBVSinsto{\c{C}anakkale Onsekiz Mart University, Department of
Physics, \c{C}anakkale, Turkey \\ \indent
email: ozdemir@mail.comu.edu.tr, demircan@comu.edu.tr}

\SIMBADobjAlias{V899 Her}{HD 149684}

\begintext

The relatively bright EW type binary V899 Her (HD 149684 =
BD\,+33\deg2748, $\alpha_{2000}=16\hr35\mm02\fsec0$,
$\delta_{2000}=+33\deg12\arcm48\farcs0$) was first discovered by
HIPPARCOS (ESA, 1998). The photometric observations of the system by
HIPPARCOS show a W UMa type light curve with an amplitude of 0\fmm121
ranging from 7\fmm935 to 8\fmm056 and with two equal minima depths. The
mean orbital period derived by HIPPARCOS from the best light curve fit
is 0\fday421173 and the epoch is given as JD 2448500.136 (ESA, 1998).
The spectral type of the system is given as F8.

The first ground-based observations of V899 Her were made on 2 nights
during 2000 observing season with the same equipments and technique
described by \"Ozdemir et al.\ (2001). The comparison star is
BD\,+33\deg2771 (HIP 81763), and the check stars are BD\,+34\deg2826
(HIP 81732), BD\,+34\deg2799 (HIP 80806), BD\,+34\deg2820 (SAO 65448),
and BD\,+34\deg2776 (HIP 80279). Differential magnitudes, in the sense
checks minus comparison, were used to determine the standard errors
(which are 0\fmm020, 0\fmm016, and 0\fmm021) of our observations in
$U$, $B$ and $V$ bands, respectively.

The light and color curves were plotted in Figure~1 together with
the HIPPARCOS light curve. The light level estimates by taking a
$\Delta \Phi =\pm 0.03$ interval around the maxima and minima,
and their differences are listed in Table~1. It can be seen in
Figure~1 and Table~1 that the maxima of all light curves,
especially in $U$ band, show a marginal evidence of being unequal
with exhibiting slightly higher maxima at 0.25. There is not any
clear evidence for the asymmetry in the light curves. A new minima
time is derived from the observations by using the Kwee and van
Woerden (1956) method and given in Table~2, together with
Hipparcos' determination. These minima times were used in forming
the $O-C$ diagram of V899 Her and were fitted by a linear function
to obtain a new light element of the system:
\begin{equation}
{\rm H.J.D.\ Min~I} = 2448500.13600 + 0\fday42117220(4) \times E.
\end{equation}

We acknowledge the observing time at the Ankara University Observatory,
and the partial support by the Research Fund of \c{C}anakkale Onsekiz
Mart University.

\begin{table}
\caption{The light levels and their differences in the light
curves of V899 Her}
\begin{center}
\begin{tabular}{lrrrr}
\hline
 & \multicolumn1c{$u$} & \multicolumn1c{$b$} & \multicolumn1c{$v$} & HIP \\
\hline
Max.\ light at 0.75 & 0.007 & $-0.026$ & $-0.071$ & 7.935 \\
Max.\ light at 0.25 & $-0.008$ & $-0.029$ & $-0.075$ & 7.939 \\
Min.\ light at 0.00 & 0.131 & 0.109 & 0.065 & 8.056 \\
Min.\ light at 0.50 & 0.141 & 0.102 & 0.061 & 8.054 \\
$\Delta$max.\ ($m_{0.75}-m_{0.25}$) & 0.015 & 0.003 & 0.004 & $-0.004$ \\
$\Delta$min.\ ($m_{0.00}-m_{0.50}$) & $-0.010$ & 0.007 & 0.004 & 0.002 \\
Depth of Min.\ I & 0.132 & 0.137 & 0.138 & 0.119 \\
Depth of Min.\ II & 0.142 & 0.130 & 0.134 & 0.117 \\
\hline
\end{tabular}
\end{center}

\caption{All available minima times of V899 Her. The $O-C$ values
were calculated by using the improved ephemeris}
\begin{center}
\begin{tabular}{lcccl}
\hline
JD Hel. & \lower6pt\hbox{Min} & \lower6pt\hbox{Filter} & \lower6pt\hbox{$O-C$} & \lower6pt\hbox{Reference} \\
2400000\,+ & & \\
\hline
48500.13600 & I & & 0.0 & HIPPARCOS ESA (1998) \\
51708.415(26) & II & $UBV$ & 0.0 & This work \\
\hline
\end{tabular}
\end{center}
\end{table}

\IBVSfig{12cm}{5034-f1.eps}{The light and color curves of V899 Her}

\newpage

\references

ESA, 1998, The Hipparcos \& Tycho Catalogues, SP--1220

Kwee, K.K., and van Voerden, H., 1956, {\it B.A.N.}, {\bf 12}, 327

\"Ozdemir, S., Demircan, O., Erdem, A.; \c{C}i\c{c}ek, C.; Bulut,
\.{I}., Soydugan, F., Soydugan, E., 2001, {\it IBVS}, No.\ 5033

\endreferences

\vskip 3cm

\IBVSerratum{4941}

In IBVS 4941 a minimum time (2448383.4256) of BO CVn is wrong.
The correct value is 2448383.4156.

\bigskip

Berahitdin ALBAYRAK

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